1. Field
This patent specification relates to a laser beam scanning system, and more particularly to a beam scanning system in use for Carlson-type image recording, having a reduced size, power consumption, costs and operation noise, and achieving excellent image quality and high scan speeds.
2. Discussion of the Background
As an exemplary method of laser beam scanning, a method using a rotating polygonal mirror is well known, and appears to continue as a viable means for achieving duplication and printing with excellent image quality and high turnaround speeds. It is noted, however, the method has drawbacks to solve such as, for example, reduction in size, costs and noise during operation. In order to attain higher speeds, several methods employing multi-beams have been investigated (as exemplified by, for example, Optics 24th Symp. Proc. 17-18 (1999)).
Another method of laser beam scanning is also known which utilizes a light emitting device (LED) array. This method has been developed and put into market primarily in order to reduce the machine size. Although it has not been recognized as the mainstay of scanning systems, efforts continue to implement it as one of the ideal forms of the system. The efforts at present are focused on higher image quality and reduced costs. Although LED devices, as the constituents of the array, preferably have to be zero in defect and each to have required characteristics, there are still expected various difficulties in achieving these goals with satisfactory production yield. (For example, Oki Electronic Industry, R and D Reports, Vol. 54, No. 1, 31-38 (1997)).
In the scanning system, therefore, further improvements are desirable to implement laser beam scanning system which is, in particular, capable of achieving reciprocal scans transverse to the axial direction of the photosensitive drum. This system is preferably constructed with a reduced size, power consumption, costs and operation noise, still retaining excellent image quality and high turnaround speeds, without incorporating mechanical devices such as, for example, a rotating polygonal mirror.
Accordingly, it is an object of the present disclosure to provide an improved laser beam scanning system, having most, if not all, of the advantages and features of similar employed systems, while eliminating many of the aforementioned disadvantages.
The following brief description is a synopsis of only selected features and attributes of the present disclosure. A more complete description thereof is found below in the section entitled xe2x80x9cDescription of Preferred Embodimentsxe2x80x9d.
A laser scanning system disclosed herein includes a wavelength tunable laser generating and emitting a laser beam having tunable wavelengths, and at least one photonic crystal receiving the laser beam emitted from the wavelength tunable laser. The photonic crystal deflects the received laser beam, during propagation within the photonic crystal, at an angle depending on the wavelength of the laser beam, and emits the deflected laser beam at various angles of emission depending on the angle deflected in the photonic crystal to thereby scan the laser beam over the surface area of a body to be scanned.
In another aspect disclosed herein, the non-linearity found in the wavelength versus scanning beam position relation is suitably adjusted with position sensors provided at both ends, and in between positions, of the beam scanning range on the photosensitive member. With this configuration of the position sensors, the above-mentioned non-linearity is compensated, and also beam scanning with high precision becomes feasible.
In still another aspect disclosed herein, a device is provided for varying the angles of emission for a light beam emitted from the device in place of the above noted wavelength tunable laser, which is useful for achieving higher angles of deflection, thereby leading to a more compact construction of the laser beam scanning system.